A256630 Numbers n such that the decimal expansions of both n and n^2 have 0 as smallest digit and 4 as largest digit.

142201, 1422010, 11141110, 11411110, 11412021, 14220100, 20323421, 21024111, 101203421, 110141011, 110142201, 111411100, 114111100, 114120210, 120013421, 141433102, 142201000, 203234210, 210241110, 1012034210, 1101410011, 1101410110, 1101422010, 1114111000

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Mathematica

fQ[n_] := Block[{c = DigitCount@ n}, And[Plus @@ Take[c, {5, 9}] == 0, c[[4]] > 0, c[[10]] > 0]]; Select[Range@ 10000000, fQ@ # && fQ[#^2] &] (* Michael De Vlieger, Apr 12 2015 *)

Prog

(PARI) is(n) = vecmin(digits(n))==0 && vecmin(digits(n^2))==0 && vecmax(digits(n))==4 && vecmax(digits(n^2))==4
(Python)
from itertools import product
A256630_list = []
for l in range(11):
    for a in ('1', '2', '3', '4'):
        for b in product('01234', repeat = l):
            for c in ('0', '1', '2'):
                s = a+''.join(b)+c
                if '0' in s and '4' in s:
                    n = int(s)
                    s2 = set(str(n**2))
                    if {'0', '4'} <= s2 <= {'0', '1', '2', '3', '4'}:
                        A256630_list.append(n)
print(A256630_list) # Chai Wah Wu, Apr 17 2015

Crossrefs

Cf. A256631, A256633, A256634, A256708, A256709, A256889.

Subsequence of A136810.

Sequence in context: A214479 A269321 A204287 * A263037 A086999 A175694

Adjacent sequences: A256627 A256628 A256629 * A256631 A256632 A256633

Keyword

nonn,base

Author

Felix Fröhlich, Apr 05 2015

Extensions

More terms from Alois P. Heinz, Apr 16 2015

Status

approved